Signal Amplification for Cell-Free Biosensors, an Analog-to-Digital Converter.

Toehold switches are biosensors useful for the detection of endogenous and environmental RNAs. They have been successfully engineered to detect virus RNAs in cell-free gene expression reactions. Their inherent sequence programmability makes engineering a fast and predictable process. Despite improvements in the design, toehold switches suffer from leaky translation in the OFF state, which compromises the fold change and sensitivity of the biosensor. To address this, we constructed and tested signal amplification circuits for three toehold switches triggered by Dengue and SARS-CoV-2 RNAs and an artificial RNA. The serine integrase circuit efficiently contained leakage, boosted the expression fold change from OFF to ON, and decreased the detection limit of the switches by 3-4 orders of magnitude. Ultimately, the integrase circuit converted the analog switches' signals into digital-like output. The circuit is broadly useful for biosensors and eliminates the hard work of designing and testing multiple switches to find the best possible performer.

Liberal Versus Restrictive Transfusion Strategy in Critically Ill Oncologic Patients: The Transfusion Requirements in Critically Ill Oncologic Patients Randomized Controlled Trial.

OBJECTIVE: To assess whether a restrictive strategy of RBC transfusion reduces 28-day mortality when compared with a liberal strategy in cancer patients with septic shock. DESIGN: Single center, randomized, double-blind controlled trial. SETTING: Teaching hospital. PATIENTS: Adult cancer patients with septic shock in the first 6 hours of ICU admission. INTERVENTIONS: Patients were randomized to the liberal (hemoglobin threshold, < 9 g/dL) or to the restrictive strategy (hemoglobin threshold, < 7 g/dL) of RBC transfusion during ICU stay. MEASUREMENTS AND MAIN RESULTS: Patients were randomized to the liberal (n = 149) or to the restrictive transfusion strategy (n = 151) group. Patients in the liberal group received more RBC units than patients in the restrictive group (1 [0-3] vs 0 [0-2] unit; p < 0.001). At 28 days after randomization, mortality rate in the liberal group (primary endpoint of the study) was 45% (67 patients) versus 56% (84 patients) in the restrictive group (hazard ratio, 0.74; 95% CI, 0.53-1.04; p = 0.08) with no differences in ICU and hospital length of stay. At 90 days after randomization, mortality rate in the liberal group was lower (59% vs 70%) than in the restrictive group (hazard ratio, 0.72; 95% CI, 0.53-0.97; p = 0.03). CONCLUSIONS: We observed a survival trend favoring a liberal transfusion strategy in patients with septic shock when compared with the restrictive strategy. These results went in the opposite direction of the a priori hypothesis and of other trials in the field and need to be confirmed.

Effect of Perioperative Goal-Directed Hemodynamic Resuscitation Therapy on Outcomes Following Cardiac Surgery: A Randomized Clinical Trial and Systematic Review.

OBJECTIVES: To evaluate the effects of goal-directed therapy on outcomes in high-risk patients undergoing cardiac surgery. DESIGN: A prospective randomized controlled trial and an updated metaanalysis of randomized trials published from inception up to May 1, 2015. SETTING: Surgical ICU within a tertiary referral university-affiliated teaching hospital. PATIENTS: One hundred twenty-six high-risk patients undergoing coronary artery bypass surgery or valve repair. INTERVENTIONS: Patients were randomized to a cardiac output-guided hemodynamic therapy algorithm (goal-directed therapy group, n = 62) or to usual care (n = 64). In the goal-directed therapy arm, a cardiac index of greater than 3 L/min/m was targeted with IV fluids, inotropes, and RBC transfusion starting from cardiopulmonary bypass and ending 8 hours after arrival to the ICU. MEASUREMENTS AND MAIN RESULTS: The primary outcome was a composite endpoint of 30-day mortality and major postoperative complications. Patients from the goal-directed therapy group received a greater median (interquartile range) volume of IV fluids than the usual care group (1,000 [625-1,500] vs 500 [500-1,000] mL; p < 0.001], with no differences in the administration of either inotropes or RBC transfusions. The primary outcome was reduced in the goal-directed therapy group (27.4% vs 45.3%; p = 0.037). The goal-directed therapy group had a lower occurrence rate of infection (12.9% vs 29.7%; p = 0.002) and low cardiac output syndrome (6.5% vs 26.6%; p = 0.002). We also observed lower ICU cumulative dosage of dobutamine (12 vs 19 mg/kg; p = 0.003) and a shorter ICU (3 [3-4] vs 5 [4-7] d; p < 0.001) and hospital length of stay (9 [8-16] vs 12 [9-22] d; p = 0.049) in the goal-directed therapy compared with the usual care group. There were no differences in 30-day mortality rates (4.8% vs 9.4%, respectively; p = 0.492). The metaanalysis identified six trials and showed that, when compared with standard treatment, goal-directed therapy reduced the overall rate of complications (goal-directed therapy, 47/410 [11%] vs usual care, 92/415 [22%]; odds ratio, 0.40 [95% CI, 0.26-0.63]; p < 0.0001) and decreased the hospital length of stay (mean difference, -5.44 d; 95% CI, -9.28 to -1.60; p = 0.006) with no difference in postoperative mortality: 9 of 410 (2.2%) versus 15 of 415 (3.6%), odds ratio, 0.61 (95% CI, 0.26-1.47), and p = 0.27. CONCLUSIONS: Goal-directed therapy using fluids, inotropes, and blood transfusion reduced 30-day major complications in high-risk patients undergoing cardiac surgery.